DE 603 04 663 T2 discloses a hydraulic valve arrangement with a supply connector arrangement including a high pressure connector P and a low pressure connector T. A working connector arrangement having two working or utility connectors A, B can be connected to a consumer, a directional valve, and a compensation valve located between the directional valve and the supply connector arrangement P, T. The pressure output of the supply connector arrangement is connected to the pressure input of the directional valve. The compensation valve has a relief output that can be connected to the pressure output and a valve element in the form of a spool that can be moved out of an initial position in opposite directions. The spool can be exposed on one side to pressure in the load sensing line and to the force of a spring, and on the opposite side can be exposed to the pressure at the pressure output. The valve element, when moved in one direction performs a pressure control function, and when moved in the opposite direction performs a pressure relief function. The spool has a longitudinal channel connected via a transverse bore to the pressure output and ends in a first pressure chamber. The longitudinal channel extends beyond the transverse bore and is connectable via a closable opening to a second pressure chamber in which a relief pressure prevails.
With this known solution, parasitic pressure propagation, as can occur especially at higher pressures, can be counteracted. With the accompanying essentially inevitable leaks, the pressure propagates as far as an actuation motor that should not be actuated at all, but then sets it into motion. This actuation can result in the unintended and hazardous raising of loads. In this connection, the safety valves have been used in the past but, can be subject to leaks and can even contribute to the formation of the parasitic pressure propagation.
EP 1 370 773 B1 discloses a comparable directional control valve as a hydraulic valve device used for controlling the pressure and the flow of hydraulic oil from and to working connectors A, B of at least one fluid consumer. The pressure and flow rate can be controlled by a valve spool movable in the spool bore and actuatable by at least one drive. By annular channels dynamically connected to it, at a symmetry center point on the axis of symmetry of the valve device, a tank connector annular channel as a return flow connector and on both sides other annular channels are arranged likewise symmetrically to the axis of symmetry. Due to the symmetrical structure, this known solution has a simple solution from a mechanical viewpoint and thus allows economical fabrication. The known valve device is intended to also have improved dynamic switching behavior and a wide scope of operation.
The known solutions, however, overall are still complex in production. For any fluidic application generally, each must be matched and designed accordingly. The known solutions in the prior art with respect to operating reliability still leave much to be desired.